460 Theory of the Nutrition [BOOK in. 



parts of the plant, where it is the means of maintaining growth 

 and nutrition. These later remarks also are better than much 

 that was said about the movement of the sap in the iSth and 

 even in the igth century, and at all events they prove that to 

 speak of Malpighi as a defender of the circulation of the sap in 

 Major's sense, as was often -done in later times, was an entire 

 misunderstanding of his views. 



Malpighi published his theory in a brief and connected form 

 in 1671 ; it appeared again further worked out in detail in the 

 fuller edition of the Phytotomy in 1674 ; he attributed a special 

 value to his discovery, that plants require air to breathe as 

 much as animals, and that the vessels of the wood answer in 

 function to the tracheae in insects and to the lungs in other 

 animals; he recurs also several times to the importance of 

 leaves as organs for the elaboration of the food. 



If we compare Malpighi's theory of the nutrition of plants 

 with the views of his predecessors, we cannot help seeing, that 

 it was an entirely new creation, in which Aristotelian doctrines 

 had no share. If his successors had apprehended the impor- 

 tant and essential points in his doctrine and had striven by 

 experimenting on living plants to support and illustrate them 

 by new facts, we should have been spared many erroneous 

 notions which established themselves in the theory, and made 

 it a perfect chaos of misconceptions. That particular miscon- 

 ception, which we have already mentioned more than once, 

 namely, that Malpighi, like Major and Perrault after him, 

 assumed a continuous circulation of the juices of the plant, 

 necessarily involved an incorrect idea of the function of the 

 leaves ; that function was by many later writers either quite 

 neglected, or sought for chiefly in transpiration, the chemical 

 activity of the leaves being quite overlooked. 



Malpighi's theory can hardly be said to take into considera- 

 tion the chemical nature of the food of plants ; it is chiefly 

 occupied with the relation of the organs to the main points in 

 the nutritive process ; its foundations are for the most part 



